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Tuesday, 19 May 2009

Automation objects and State Based Control

State based control is a method of defining the required states of some equipment and then driving the equipment to one of these states, typically where a Phase step sets the Equipment States.It is an excellent way of describing the required behaviour of an Automation Object, or at least what I think of as an automation object. But I cannot relate it to Part 5 as it stands.In essence designing a state controlled automation object involves in a large part determining all the required states that you need to set that object to. Please note that these States are not comparable to the Part 1 or 5 'Procedural States', they are things like Open, Closed, Ready to Fill, Filling, Reacting etc.ControlDraw has long supported this method because it provides a very efficient method of representing functional requirements. And consequently over the 10+ years of designing systems with ControlDraw I now have designs for hundreds of these. You can read more here and here.They range from basic control modules like motors and valves to highly intricate units, such as BioReactors, semi continuous sterilizers etc.And looking at these, they have never needed to contain Resource Management. Yes they may have properties that relate to Resource Management, but always the actual Resource Manager is outside them. The lower level ones such as PID Controllers, are contained in Equipment Modules or Units, and the Resource Manager does not look at them, it only deals with the higher levels.This is one reason for my objections to Part 5 as it stands. But please understand that I don't want to spend my time complaining about Part 5, I want to contribute positively.

As it stands, I cannot. I think it should be completely re-started or abandoned.